Abstract
Purpose :
The purpose of this study was to compare the performance of 7 IOL power prediction formulas in axial myopes.
Methods :
Retrospective consecutive case series of eyes with axial length (AL) greater than 25.0 mm that underwent cataract extraction with implantation of a monofocal IOL (Akreos AO60, Bausch & Lomb) between January 2016 and October 2018 by a single surgeon. Eyes were excluded if they had history of surgery or trauma, inflammatory conditions, intraoperative complication, cataract surgery combined with another procedure, or a postoperative best-corrected visual acuity worse than 20/40. Residual refractive error for each eye was predicted for the implanted IOL using 7 formulas (Holladay1 [H1], Linear Wang-Koch adjusted Holladay1 [l-WKH1], SRK/T, Barrett II Universal [BU-II], Hill-RBF v3.0, EVO, and Kane). The same nominal A-constant (118.4) was used in all formulas. Prediction error was calculated as the difference between the actual and predicted spherical equivalent (SE). Mean prediction errors (MPEs) and absolute errors (MAEs) were compared using a Friedman with Dunn post-test. Comparison of proportions was done using a Cochran Q test with McNemar’s post-test.
Results :
Among the 200 study eyes, the MPE was 0.36 ± 0.51, 0.00 ± 0.53, 0.22 ± 0.52, 0.11 ± 0.46, 0.23 ± 0.48, 0.09 ± 0.47, and 0.13 ± 0.47 D for H1, l-WKH1, SRK/T, BU-II, Hill-RBF, EVO, and Kane, respectively (p < 0.0001). The MAEs were 0.48 ± 0.40, 0.39 ± 0.36, 0.41 ± 0.38, 0.35 ± 0.33, 0.40 ± 0.35, 0.35 ± 0.32, and 0.36 ± 0.32 D, respectively (p < 0.0001). The proportion of eyes within 0.5 D of predicted SE was 60.5%, 71%, 68%, 76%, 70.5%, 76.5%, and 74%, respectively, with BU-II and EVO each performing better than H1, l-WKH1, SRK/T, and Hill-RBF (p<0.0001). EVO (p < 0.0001), but not BU-II (p = 0.49) performed better than Kane with regards to this metric. There was no significant difference between BU-II and EVO regarding proportion of eyes within 0.25, 0.5, 0.75, or 1.0 D of predicted SE. Hyperopic prediction errors occurred in 82%, 49%, 71.5%, 61.5%, 73%, 61%, and 66.5% of eyes, respectively (p < 0.0001), with SRK/T being similar to Hill-RBF (p = 1.0) and BU-II being similar to EVO (p = 1.0).
Conclusions :
The l-WKH1 improves outcomes over H1. Modern formulas (BU-II, EVO, Hill-RBF, and Kane) outperform older ones (H1 and SRK/T). An AL adjustment or modern formula should be used when performing IOL power calculations in axial myopes.
This is a 2021 ARVO Annual Meeting abstract.